Alkylation of saturated hydrocarbons

ABSTRACT

Saturated hydrocarbons are alkylated by treatment with an olefinic hydrocarbon as the alkylating agent, the reaction being effected by contacting the alkylation mixture with hydrogen chloride and an oxygencontaining gas at a temperature in the range of from about 100* to about 400* C. and a pressure in the range of atmospheric to about 100 atmospheres.

baited @tates Patent 1191 Sehmeriing Dec. 17, 1974 [5 1 ALKYLATION OF SATURATED 2,557,114 6/1951 Kennedy et a1 260/683.47 HYDROCARBONS 2,562,217 7/1951 Schmerling 260/683.47 3,240,840 3 1966 Goble et a1. 260/683.47 [75] Inventor: L i m rl g, Riverside, 3,306,950 2/1967 Bajars 260 666 A 3,763,270 10 1972 Schmerling 260/68347 [73] Asslgnee' unwerszflo" Pmducts 3,764,637 10/1973 Lyon 260/683.47 Des Flames 3,773,843 11/1973 Schmerling 260/683.47

[22] Filed: Aug. 15, 1973 App]. No.: 388,696

Related U.S. Application Data Continuation-impart of Ser. No. 212,721, Dec. 27, 1971, abandoned.

Primary ExaminerDelbert E. Gantz Assistant Examiner-Veronica OKeefe Attorney, Agent, or Firm-James R. Hoatson, Jr.; Raymond H. Nelson; William H. Page, 11

[5 7] ABSTRACT 10 Claims, N0 Drawings 1 ALKYLATION OF SATURA'I'ED HYDROCARBONS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 212,721 filed Dec. 27, 1971 now abandoned.

BACKGROUND OF THE INVENTION another prior art reference has also disclosed the alkylation of isobutane with propene using oxygen and a halogen derivative of a hydrocarbon as catalyst. Among the halogenated hydrocarbons which are mentioned by these references are chloroform, carbon tetrachloride, l,2,3-trichloropropane, benzene chloride, propylene tribromide, propylene dibromide, and ethyl bromide. The process of these references may be illustrated by the following equations:

R can Rcrnom Romormomorrmomcrrz lRI-I R formed in the last equation starts a new cycle as in the third equation.

For example, as will hereinafter be shown in greater detail, the reaction of a saturated hydrocarbon such as cyclohexane with an olefin such-as ethylene in the presence of oxygen yields a product which consists of high molecular weight alkylate, said alkylate consisting of a mixture of ethyl-, butyl-, hexyl-, octyl-, decyl-, dodecyland tetradecyleyelohexanes along with even much higher molecular weight hydrocarbons.

In contradistinction to this, I-have now discovered that in the oxygen-induced alkylation of saturated hydrocarbons such as cyclohexane with olefins such as ethylene, the presence of added hydrogen chloride unexpectedly results in the obtention of a product consisting almost exclusively of monoethylcyclohexane together with a very minor amount of diethylcyclohexane ular weight hydrocarbons are more plentiful in supply but may not be useful as such. They may be converted to usefiil and desired compounds by the process of this invention. For example, neohexane, which is usefulas a component of motor and aviation fuels where very high octane ratings are desirable, may be prepared according to the process hereinafter set forth in greater detail utilizing isobutane and ethylene, both of which are in plentiful supply, as the starting materials. Likewise ethylcyclohexane which is used as a fuel and in various organic syntheses may be obtained from ethylene and cyclohexane. This is also true in the preparation of dimethylpentanes and dimethylhexanes which are also used as fuel components and as intermediates in organic syntheses of various other products.

and butylcyclohexane. It was definitely unexpected that the presence of such an additive had such a desirable remarkable effect, namely, stopping the alkylation chain such that the product is of low rather than high molecular weight. g

This invention relates to a process for the alkylation of saturated hydrocarbons. More specifically the invention is concerned with a process for obtaining relatively low molecular weight alkylation products in which a saturated hydrocarbon is alkylated by treating said hydrocarbon with an olefinic hydrocarbon in the presence of hydrogen chloride and an oxygencontaining gas.

Many chemical compounds are more desirable for various reactions than others. The relatively low molec- It is therefore an object of this invention to provide a process for the alkylation of saturated hydrocarbons utilizing an olefinic hydrocarbon as the alkylating agent.

A further object of this invention is to provide a process for the alkylation of saturated hydrocarbons in which the process is'effected in the presence of a hydrogenchloride compound and an oxygen-containin gas.

In one aspect an embodiment of this invention resides in a process for the alkylation of asaturated hydrocarbon containing from about 3 to about 12 carbon atoms per molecule which consists essentially of reacting said hydrocarbon with an olefinic hydrocarbon containing from 2 to about 10 carbon atoms per molecule in contact with free hydrogen chloride and an' oxygencontaining gas at reaction conditions, and recovering the resultant alkylated saturated hydrocarbon.

A specific embodiment of this invention is found in a process for the alkylation of a saturated hydrocarbon which comprises treating cyclohexane with ethylene in the presence of hydrochloric acid and air at a temperature in the range of from about to about 400 C. and a pressure in the range of from about atmospheric to about 100 atmospheres and recovering the resultant ethylcyclohexane.

Other objects and embodiment will be found in the following further detailed description of the present invention. v

As hereinbefore set forth, it has now been discovered that by alkylating a saturated hydrocarbon with an olefinic hydrocarbon in the presence of an oxygencontaining gas and added hydrogen chloride, it is possible to obtain a product which comprises a low molecular weight alkylation product. This was unexpected inasmuch as no other known additive possesses the remarkable property exhibited by hydrogen chloride or an aqueous solution thereof, namely, the ability to stop the alkylation chain so that the product is of low rather R- which is formed in this last equation starts a new cycle as in the first equation and RCH CH is the chief product due to the presence of the hydrogen chloride rather than R(CH CH ),,H (where n is substantially greater than 2).

Thus, it will be readily seen that the hydrogen chloride acts as a chain terminator thereby markedly reducing the amount of the high molecular weight telomers which are produced in an undesired manner in the present processes of the prior art.

Olefinic hydrocarbons which may be used as alkylating agents in the process of the present invention will include olefins containing from 2 up to about carbon atoms in length, being both straight chain, branched chain and cyclic in configuration. Some representative examples of these olefins will include ethylene, propene, l-butene, 2-butene, l-pentene, 2- pentene, l-hexene, 2-hexene, 3-hexene, l-heptene, 2-

heptene, 3-heptene, l-octene, 2-octene, 3-octene, 4- I octene, the isomeric straight chain nonenes and decenes, 2-methyl-l-propene (isobutylene), 2-methyl-lbutene, 2-methyl-2-butene, 2-methyl-l-pentene, 2-methyll -hexene, 2-methyll -heptene, 2-methyll octene, 2,3-dimethyll-pentene, 2,3-diemthyl-lhexene, 2,3-dimethyll -heptene, 2,3-dimethyll octene, etc., cyclopentene, cyclohexene, etc. In general, the olefins which contain no tertiary carbon atoms are preferred. It is to be understood, as was the case with the saturated hydrocarbons, that the aforementioned olefmic hydrocarbons are only representative of the class of alkylating agents which may be used, and that the present invention is not necessarily limited thereto.

The reaction conditions under which the alkylation process of the present invention is effected will include temperatures ranging from about 100 C. up to about 400 C. or more, the preferred range being from about 160 C. to about 260 C. In addition, the reaction may be effected under varying conditions of pressure, said pressures ranging from atmospheric up to about 100 atmospheres or more, the preferred operating pressures of the process being that which is required to maintain a substantial portion of the reactants in the liquid phase. The superatmospheric pressures at which the process may be effected will be provided for by various gases. For example, the olefinic hydrocarbon or the saturated hydrocarbon which may form one or both of the reactants of the present process may be in gaseous form and therefore these reactants will provide at least part of the desired operating pressure, the remainder being afforded by the oxygen-containing gas such as air or oxygen, the oxygen in these gases being present in uncombined form (that is, as the diatomic molecule). Alternatively, if both of the reactants, namely, the saturated hydrocarbon and the olefinic hydrocarbon, are in liquid form, the superatmospheric pressures which are utilized may be afforded by the introduction of the oxygen-containing gas and a substantially inert gas such as nitrogen into the reaction zone. In the preferred embodiment of the invention the oxygencontaining gas is present in such an amount so that the oxygen in said gas is present in a mole ratio of from about 0.00l:l up to about 1:] moles of oxygen per mole of saturated hydrocarbon, although greater and lesser amounts may also be used.

In addition, as hereinbefore set forth, the alkylation of the saturated hydrocarbon with the olefinic hydrocarbon is effected in the presence of a hydrogen chloride compound in the reaction mixture, said hydrogen chloride compound having a desirable and unexpected effect upon the alkylation by acting as a reaction-chain terminator which markedly decreases the formation of undesired higher molecular weight telomers. The hydrogen chloride compound may be present as anhydrous hydrogen chloride or as an aqueous solution of hydrogen chloride (that is, hydrochloric acid), the hydrogen chloride being present in an amount of from about 5 percent to about 38 percent in said aqueous solution.

The process of this invention may be effected in any suitable manner and may comprise either a batch or continuous type operation. For example, when a batch type operation is used, a quantity of the saturated hydrocarbon, if in liquid fomi, and hydrogen chloride are placed in an appropriate apparatus which may comprise an alkylating flask or an autoclave of the rotating or mixing type along with the desired hydrogen chloride compound. The olefinic hydrocarbon which acts as the alkylating agent is thereafter charged to the reactor with the oxygen-containing gas. If the process is effected utilizing a gaseous alkylating agent, or saturated hydrocarbon, or if the process is to be effected at superatmospheric pressures, the reactor is sealed, pressurized to the desired operating pressure and thereafter heated to a predetermined reaction temperature. As hereinbefore set forth, the desired operating pressure is provided for by the gaseous reactants, the oxygencontaining gas, a substantially inert gas or a combination of two or more of the preceding gaseous elements. The reaction is effected at the desired operating temperature for a period which may range from about 0.5 up to about 10 hours or more in duration, after which heating is discontinued, the reaction vessel is allowed to return to room temperature and any excess pressure, if present, is discharged. The reaction mixture is recovered, separated, washed, dried, and subjected to conventional means of separation suchas fractional distillation under atmospheric or reduced pressure, etc.

whereby the desired alkylated saturated hydrocarbon is separated and recovered.

It is also contemplated within the scope of this invention that the alkylation of the saturated hydrocarbon with the Olefinic hydrocarbon may be effected in a continuous manner of operation. When such a type of operation is used, the satuarated hydrocarbon which is to undergo alkylation and the olefinic hydrocarbon which acts as the alkylating agent are continuously charged to a reaction zone which is maintained at the proper operating conditions of temperature and pressure and which contains the hydrogen chloride compounds. In

addition, the oxygen-containing gas and hydrogen chloride are also charged to the reactor in an amount so that oxygen is present in the reaction zone in an amount within the range hereinbefore set forth in greater detail. It is contemplated that the reactants for the present process may be charged to the reactor through separate lines, or. if so desired, they may be admixed prior to entry into said reactor and charged thereto in a single stream. Upon completion of the desired residence time, the reactor effluent is continu- The following examples are given to illustrate the process of the present invention; however, they are not intended to limit the generally broad scope of the present invention in strict accordance therewith.

EXAMPLE 1 In this example grams of water and 134 grams (1.60 moles) of cyclohexane were placed in the glass liner or a rotating autoclave. The autoclave was sealed and 40 atmospheres of ethylene (about 1.3 moles) was charged thereto. In addition there was present 1 atmosphere of air corresponding to about 0.006 mole oxygen. The autoclave was heated to a temperature of 180 C. and maintained thereat for a period of 8 hours. At the end of this time, heating was discontinued, the autoclave was cooled to room temperature, the final pressure at room temperature being 28 atmospheres. The

EXAMPLE ll This example illustrates the marked effect of hydrogen chloride. A glass liner containing 131 grams of cyclohexane 1.56 moles) and 50 grams of 19 percent hydrochloric acid was sealed into an autoclave which contained, as in Example I, 1 atmosphere or 0.006 mole of oxygen. Following this 40 atmospheres of ethylene was charged to the autoclave which was then heated to a temperature of 180 C. and maintained thereat for a period of 8 hours. At the end of the 8-hour period, heating was discontinued, the autoclave was cooled, the final pressure at room temperature being 24 atmospheres. The excess pressure was discharged and the autoclave was opened. The reaction product which consisted of 2 water-white liquid layers was recovered and separated. The upper organic layer was washed with water, dried over potassium carbonate and subjected to fractional distillation. There-was obtained 5 grams of the desired product comprising ethylcyclohexane as an overhead which boiled chiefly at l-l35 C. In addition, there was also obtained 3 grams of pale yellow liquid bottoms which was shown by gas-liquid chromatography to consist chiefly of ethylcyclohexane together with a very minor amount (no more'than 1 gram) of diethylcyclohexanes and butylcyclohexanes. The yield of monoethylcyclohexane corresponded to about 5 percent of the theoretical yield based on the ethylene charged.

ltis therefore readily apparent from a comparison of Examples 1 and II that it is possible to alkylate a saturated hydrocarbon with an olefinic hydrocarbon as the alkylating agent in an alkylation process which is effected in the presence of an oxygen-containing gas such as air and a hydrogen chloride compound such as hydrochloric acid which acts as a chain terminator thereby reducing the amount of higher molecular weight telomers while permitting the obtention of the desired monoalkylated and moderately alkylated saturated hydrocarbons.

EXAMPLE Ill When Example II above was repeated utilizing a tem-' perature of 250 C. for a period of 8 hours with the same amounts of cyclohexane, ethylene, air and hydrochloric acid as was used in Example II, a product comprising 11' grams of monoethylcyclohexane was obtained (an 8 percent yield) together with only 1 gram of higher molecular weight product.

EXAMPLE IV I This example illustrates the effect of reaction time and of an increased concentration of oxygen. A glass liner containing 131 grams of cyclohexane (1.56. moles) and 50 grams of 19 percent hydrochloric acid was sealed into an autoclave and thereafter Satmo spheres of air was pressed into the sealed autoclave (the oxygen present thus amounting to about 0.05 mole) before adding the atmospheres of ethylene. The autoclave was then heated to a temperature of 180 C. and maintained thereat for a period of 8 hours. At the end of this time, heating was discontinued, the autoclave was cooled and the excess pressure was discharged. The autoclave was opened and the reaction product which was recovered therefrom was treated in a manner similar to that set forth in the above examples; that is, the organic layer was separated, washed 7 with water, dried and subjected to fractional distillation. The ethylcyclohexane which comprised the desired product, wasv obtained in a 10 percent yield. A repeat of this experiment using 10 atmospheres of air (about 0.1 mole of oxygen) resulted in increasing the yield to 14 percent.

That the relatively long reaction time which was utilized in most of the examples of this invention was unnecessary was shown by repeating the example utilizing l0 atmospheres of air and the same. concentration of the other reactants and hydrochloric acid, the only difference being that the reaction was effected at a temperature of C. for a period of 1 hour in place of the 8 hours; ethylcyclohexane was isolated in a 12 percent yield.

EXAWLE v A mixture'of 35 grams of cyclohexane-and 30 grams of l-octene is placed in the glass liner of the autoclave along with 20 grams of concentrated hydrochloric acid. After sealing the liner into the autoclave, l5 atmospheres of air is pressed in and the autoclave is heated at 200 C. for 4 hours. Upon completion of the 4-hour residence time, heating is discontinued and the reactor allowed to cool. The reaction product is recovered and treated in a manner similar to that hereinbefore described, a gas-liquid chromatographic analysis disclosing the presence of a major portion of noctylcyclohexane in the reaction product.

EXAMPLE Vl To a sealed rotating autoclave containing a glass liner, said liner containing 15 grams of concentrated hydrochloric acid and 49 grams of n-heptane, was charged 50 grams of isobutane, 100 pounds per square inch of air and 500 pounds per square inch of ethylene. The autoclave was heated to a temperature of 180 C. and maintained thereat for a period of 2 hours. Upon completion of the 2-hour period, heating was discontinued and the autoclave was allowed to return to room temperature. Upon reaching room temperature, the excess pressure was discharged and the autoclave was opened. The reaction mixture was recovered and the organic layer separated from the aqueous layer. Thereafter the organic layer was washed with water, dried over potassium carbonate and analyzed by gas chromatography. The desired product comprising 2,2- dimethylbutane (neohexane) was shown to be present.

A repeat of the above experiment omitting the presence of hydrochloric acid will disclose the fact that the reaction product does not consist chiefly of 2,2- dimethylbutane but is a mixture of higher molecular weight telomers.

EXAMPLE Vll In a manner similar to that set forth in the above examples, 127 grams (1.76 moles) of n-pentane was sealed in a glass liner of a rotating autoclave containing 50 grams 19 percent acid) of an aqueous hydrochloric acid solution. The autoclave was sealed leaving 1 atmosphere of air therein. Ethylene was pressed in until an initial operating pressure of 40 atmospheres was reached. The autoclave was then heated to a temperature of 180 C. and maintained in a range of from 180-200 C. for a period of 8 hours. At the end of the 8-hour period, the autoclave was allowed to return to room temperature, the excess pressure was discharged and the autoclave was opened. The reaction product was recovered and the upper organic layer separated from the aqueous layer. The upper layer was washed with water, dried over potassium carbonate and thereafter fractionally distilled. There was obtained 3 grams of product comprising a mixture of heptanes (73.7 percent of 3-methylhexane, 22.7 percent of 3 -ethylpentane and 3.6 percent of n-heptane) and only a trace of higher-boiling material.

EXAMPLE Vlll A glass liner containing 126 grams of cyclohexane and 23 grams of concentrated hydrochloric acid was sealed into an autoclave. Thereafter l atmospheres of air, 40 grams of propene (l0 atmospheres) and 20 atmospheres of nitrogen was pressed in. The autoclave was heated to a temperature of 180 C. and maintained thereat for a period of 4 hours following which heating was discontinued and the autoclave allowed to return to room temperature. at which temperature the pressure was 30 atmospheres. The excess pressure was discharged and the autoclave was opened. After recovery of the reaction mixture, which consisted of 2 layers, the organic layer was separated from the aqueous layer. The upper layer which was the organic layer was washed with water, dried over potassium carbonate and subjected to fractional distillation, the desired product 8 comprising n-propylcyclohexane being recovered therefrom.

EXAMPLE 1x Heating 108 grams (1.10 moles) of methylcyclohexane with 12 grams of concentrated hydrochloric acid at 180 C. for a period of 4 hours in the presence of 10 atmospheres of initial air pressure and 40 atmospheres of ethylene using the procedure described in the above experiment yielded l-methyl-lethylcyclohexane (and some isomers thereof) in about 6 percent yield. Similarly, the reaction of 118 grams (1.40 moles) of methylcyclopentane with ethylene at a temperature in the range of from 180 to 200 C. for a period of 8 hours in the presence of 1 atmosphere of initial air pressure and 29 grams of concentrated hydrochloric acid produced l-methyll -ethylcyclopentane in a 3 percent yield together with a relatively small amount of higher-boiling product.

I claim as my invention:

l. A process for the alkylation of a saturated hydrocarbon containing from about 3 to about 12 carbon atoms per molecule which consists essentially of reacting said hydrocarbon with an olefinic hydrocarbon containing from 2 to about 10 carbon atoms per molecule in contact with free hydrogen chloride and an oxygencontaining gas present in an amount of from about 0.001:1 up to about 1:1 moles of oxygen per mole of saturated hydrocarbon at reaction conditions, including a temperature of from about 160C. to about 260C. and recovering the resultant alkylated saturated hydrocarbon.

' 2. The process as set forth in claim'l in which said reaction conditions also include a pressure in the range of from about atmospheric to about atmospheres.

3. The process as set forth in claim 1 in which said oxygen-containing gas is air.

4. The process as set forth in claim 1 which said oxygen-containing gas is oxygen.

5. The process as set forth in claim 1 in which said free hydrogen chloride is in the form of hydrochloric acid.

6. The process as set forth in'claim l in which saidv saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is ethylcyclohexane. I

7. The process as set forth in claim 1 in which said saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is l-octene and said alkylated saturatedhydrocarbon is n-octylcyclohexane.

8. The process as set forth in claim 1 in which said saturated hydrocarbon is isobutane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is 2,2-dimethylbutane.

9. The process as set forth in claim 1 in which said saturated hydrocarbon is n-pentane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is a mixture of 3-methylhexane, 3- ethylpentane and n-heptane.

10. The process'as set forth in claim l'in which said saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is propene, and said alkylated saturated hydrocarbon is n-propylcyclohexane. 

1. A PROCESS FOR THE ALKYLATION OF A SATURATED HYDROCARBON CONTAINING FROM ABOUT 3 TO ABOUT 12 CARBON ATOMS PER MOLECULE WHICH CONSISTS ESSENTIALLY OF REACTING SAID HYDROCARBON WITH AN OLEFINIC HYDROCARBON CONTAINING FROM 2 TO ABOUT 10 CARBON ATOMS PER MOLECULE IN CONTACT WITH FREE HYDROGEN CHLORIDE AND AN OXYGEN-CONTAINING GAS PRESENT IN AN AMOUNT OF FROM ABOUT 0.001:1 UP TO ABOUT 1:1 MOLES OF OXYGEN PERMOLE OF SATURATED HYDROCARBON AT REACTION CONDITIONS, INCLUDING A TEMPERATURE OF FROM ABOUT 160*C. TO ABOUT 260*C. AND RECOVERING THE RESULTANT ALKYLATED SATURATED HYDROCARBON.
 2. The process as set forth in claim 1 in which said reaction conditions also include a pressure in the range of from about atmospheric to about 100 atmospheres.
 3. The process as set forth in claim 1 in which said oxygen-containing gas is air.
 4. The process as set forth in claim 1 which said oxygen-containing gas is oxygen.
 5. The process as set forth in claim 1 in which said free hydrogen chloride is in the form of hydrochloric acid.
 6. The process as set forth in claim 1 in which said saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is ethylcyclohexane.
 7. The process as set forth in claim 1 in which said saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is 1-octene and said alkylated saturated hydrocarbon is n-octylcyclohexane.
 8. The process as set forth in claim 1 in which said saturated hydrocarbon is isobutane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is 2,2-dimethylbutane.
 9. The process as set forth in claim 1 in which said saturated hydrocarbon is n-pentane, said olefinic hydrocarbon is ethylene, and said alkylated saturated hydrocarbon is a mixture of 3-methylhexane, 3-ethylpentane and n-heptane.
 10. The process as set forth in claim 1 in which said saturated hydrocarbon is cyclohexane, said olefinic hydrocarbon is propene, and said alkylated saturated hydrocarbon is n-propylcyclohexane. 